Combined muffle and open tunnel kiln



P. DLH. DRESSLEH.

COMBNED MUFFLE AND OPEN TUNNEL KILN.

. APPLICATION FILED MN. 26, |920. 1,360,625. Patented Nov. 3o, 1920.

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@Y gy Qu i i n P. DH. DHESSLER.

COMBINED MUFFLE AND OPEN TUNNEL KILN.

Patented Nov. 30, 1920.

3 SHEETS-SHEET Z- APPLICATION FILED JAN. 26| i920.

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COMBINED MUFFLE. AND OPEN TUNNEL KILN.

APPLICATION FILED JAN. 26, |920.

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@3313, Lul/d @the ww i UNITED STATES PATENT OFFICE.

PHILIP DH. VDRESSLER, OF ZANESVILLE, OHIO, ASSIGNOR TO AMERICAN DRESSLER TUNNEL KILNS, INC., 0F NEW YORK, N. Y., A CORPORATION 0F NEW YORK.

COMBINED MUFFLE AND OPEN TUNNEL KILN.

Speccaton of Letters Patent.

Patented Nov. 30, 1920.

Application led January 26, 1920. Serial No. 353,976.

To all whom t may concern.'

Be it known that I, PHILIP DH. DRnssLnR, a subject of the King of Great Britain, and resident of Zanesville, in the county of Muskingum and State of Ohio, have invented certain new and useful Improvements in Combined Mutlle and Open Tunnel Kilns, of which the following is a specilication.

My present invention relates to continuousrtunnel kilns and the general object of the invention is to effect an advantageous combination of constructivel features and advantages of the two distinct types of tunnel kilns; one of these two types of tunnel kilns being the open lire type in which all or the major portion of the heating of the goods is accomplished by direct contact of the goods with hot gaseous products of combustion, while the other type is that in which the heating of the goods is accomplished mainly or wholly by convection currents of the kiln chamber atmosphere passing through or along the goods and about combustion chambers in which combustion occurs and from which the products orn combustion are withdrawn without passing into the kiln chamber proper and without coming into contact with the goods.

The various features of novelty which characterize my invention are pointed out with particularity in the claims annexed to and forming a part of this specification. For a better understanding of the invention, however, and the advantages possessed by it, reference should behad to the accompanving drawings and descriptive matter in which I have illustrated a preferred embodiment of my invention.

Of the drawings: l,

Figure l is a vsomewhat diagrammatic plan of a kiln; y Y Y Fig. 2 is a plan of a portion ofthe apparatus shown in Fig. 1, taken on a larger scale than Fig. 1 and withV parts broken away and in section;

Fig. 3 is an elevation in section on the line 3 3 of Fig. 2;

Fig. 4 is an elevation on line 4 4 of Fig. 2.;

Fig. 5 is a view taken similarly to Fig. l illustrating a modification;

the section of the Fig. 6 is an elevation of a portion of a kiln1 illustrating a second modilication;

Fig. 7 is a plan of the apparatus shown in Fig. 6;

Fig. S is a somewhat diagrammatic plan with parts broken away and in section;

Fig. 9 is a section on the broken line 9-9 of Fig. 8; and

Fig. 10 is a partial section on the line -lO-lO of Fig. 8.

VThe cars thus entering the kiln are moved slowly through the latter and issue at the outer end of the section D which may advantageously be provided with a door KA.

I have not disclosed any mechanism for Y moving the cars through the tunnel as the details of such mechanism form no part of my present invention, and mechanisms suitable for the purpose are well known and in common use. It will be understood that the tunnel is normally filled with goods carrying cars F, one being taken out of the kiln past the door IA every time a car is inserted in the kiln past the doors K and K. To prevent the circulation of hot gases along .the track rails E and the wheels and other lower parts of the cars F, the well-known expedient may be'employed of providing the cars with-flanges F at their sides dipping into sand seals in stationary troughs F2.

The intermediate kiln section C is laterally enlarged and horizontally elongated combustion chambers I-I are located in the Vlateral enlargement of this kiln section at the sides of the pathway for the goods G.

` At the ends of the combustion chambers adjacent the outlet door KA fuel gas supply pipes I open into the combustion chambers. Air for the'combustion of this gas is ad-v mitted to the kilnchamber at the outlet endof the chamber as by means of ports L formed in the door KA. A draft is created tending to create a gaseous flow from the air inlet ports L at theopposite end of the kiln chamber by suitable means, as for instance, the exhaust fan M shown as connected to the kiln chamber adjacent the door l by the bifurcated pipe N. To force a large portion of the air thus drawn through the kiln to pass into the combustion chambers H, and through the latter instead of through the clearance space between the goods and the adjacent walls of the kiln chamber section C and combustion chambers H, one or more baflles are provided at the-corresponding ends of the combustion chamber which lit closely about the Igoods on the cars F. The kiln Vall is also advantageously inclined as indicated at C to facilitate the ready flow Vof air into the combustion chambers. At the opposite ends of the combustion chambers, the kiln wall is similarly inclined as indicated at C2 to avoid eddies and friction impeding the flow out of the combustion chambers and, in practice, the kiln wall at C2 should be lined with highly refractory material to avoid deterioration under the high temperatures of the gaseous products leaving the combustion chaml ers. The combustion chambers are so disposed with respect to the walls of the kiln chamber as to permit the circulation of conrec-4 tion currents upward past the combustion chambers and downward through and along the O'ocds. For this purpose the walls of Vthe combustion chamber may advantageonsly be formedas in the well-known Dr" "'lcr kiln of sections of hollow tile. Passages H in the tile sections unite to forni paths of loiv about the combustion chambers while at the same time the `goods are shielded against the direct radiation of heat from the inside walls of the passages H.

In operation, the fan M or other draft pro ducing device causes a continuous gaseous flow from the air inlet ports L through the section B of the kiln chamber to the adjacent ends of the combustion chambers H. The air thus brought to the combustion chambers enter the latter and unites in combustion therein with the fuel gas supplied through-the fuel gas inletsl. rlhe combustion chamber H should be of such a length, say 20 or 30 feet in ordinary practice that the fuel gas will be entirely burned in the combustion chambers and a large portion of the heat of combustion will be Withdrawn from the products of combustion and delivered to the goods through the medium of the convectionV currents flowing through the passages H and through or along the goods.

The partially cooled products of combus-V tion issuing from the exit end of the combustion chambers pass into the adjacent end of the kiln chambers B and passlongitudiA nallyV of-ithe latter to the outlet .pipes N'. The:

products of combustion entering the kiln chamber section B 'are gradually cooled in their passage through the latter, imparting their heat to the goods G in this section of the kiln.

The construction shown in Figs. 1 to et is intended for use where the goods after passing through the high temperature Zone of the kiln are cooled down to a substantial extent before being taken'out of the kiln. This is generally the case, for instance, where the kiln is used in firing pottery. ln other cases, however, as for example, in the glass industry and in steel heating furnaces, it is desirable to withdraw the goods from the kilns while still at the maximum temperature attained in the kiln. F or such cases the form of myV invention illustrated in Fig. 5 is Well adapted.

T he kiln All shown in Fig. 5 differs from thatshown in Figs. 1 to e inclusive essentially in that the cooling section D of the kiln shown in Figs. 1 to l is omitted. ln

Fig. 5 the goods outlet door 7c is placed iinmediately adjacent the exit end of the high temperature section C of the kiln, and advantageously a second door ,lm forming an air lock is provided. The air, uniting in com` Vthe flow of air from the Vkiln section D into the combustion chambers H in lieu of, or in addition to the simple expedient shown in Figs. 1 to l of laterally restricting the kiln portion D relative tothe kiln portion C and tapering the walls C. For example, as shown in Figs. 6 and 7 a fan l? may have an inlet or inlets P opening to the kiln section D and its outlet connected by conduits P2 to the combustion chambers H in the kiln section CA.

lilith each of the constructions described I obtain the following characteristic advantages of a kiln having combustion chambers of theDressler type; namely, the indestructibility of the combustion chambers due to their thin wall construction and the abstraction of heat therefrom by convection curthe burning products of combustion; and a suiiiciently elongated high-temperature Zone toV permit an adequate exposure of the gooos to the highest'kiln temperature with a reasonably rapid rate oftravel of the goods carrying cars through the tunnel I also obtain the following advantages characteristic of open fire kilns; namely, a shorter length of kiln than'is required if substantially all of the heat imparted to the goods is transmitted by conduction through combustion chamber walls; and a cheapening ot' construction due both to the shortening of the kiln as a whole, and also to the shortening of the combustion chambers relative to the length of the kiln.

In lieu of heating the high temperature zone of a kiln by Vcombustion chambers or muiies, and then passing the partially cooled products of combustion into the kiln chamber proper, I may sometimes, with advantage, heat the high temperature Zone of the kiln by combustion occurring in the kiln l chamber proper, and then divert the partially cooled products of combustion from the kiln chamber into muilles running along a zone of the kiln maintained at a somewhat lower temperature than the open lire heated high temperature zone of the kiln, and in Figs. S to l() I have illustrated a kiln AB operating in this manner. Y

The kiln AB comprises a goods cooling zone DB, a high temperature zone CB, and

a heating-up zone BB. The goods passing from the high temperature zone CB into the cooling zone DB are subjected in the latter to the cooling action of air drawn into the kiln at its exit end. As shown7 the air employed to' cool the goods is withdrawn yfrom the Zone DB through ports D10 formed in the kiln roof and pipe Q to which the Vports D10 open. Advantageously the space inV the kiln above the pathway for the goods is divided: into a series of compartments, open vat their lower ends to the goods pathway, by tran'sverse barriers C10 located one in front of each pair of ports D10. Heated air escaping from the cooling Zone portion of the kiln chamber through the ports D10 passes into pipes Q, and some or all of this air is delivered by fans PA and their outlets P1 into the ends of the conduits R.

The latter run along the high temperature zone'CB at opposite sides of the kiln. Con- Aduits D11 deliver air drawn from the compartment atthe rear of the baule C10 imlS located at each` side of the kiln chamber and distributed along they length ol the hot zone CB. Gas issupplied at the outer end of each burner chamber through a corre-V sponding burner pipe IB which extends into v perature Zone. vvantageously be and are shown as being The conduits R are .goods carrying cars FB and the goods mounted thereon. Advantageously the goods are so stacked, or the bodies of the cars FB are so formed, as to provide channels F10 open at their outer ends, and open at their upper sides to the goods above them, and so arranged as to directly receive the jets of flame and burning gases issuing from the different combustion chambers as the movement of the cars carries the channels past the different burner chambers. Advantageously also, the burner chambers and channels F10 are obliquely inclined to the direction oit' the movement of the cars as shown in Fig. 8.

The heating-up Zone BB of the kiln is laterally enlargedA at-the-sides of the pathway for the goods, to provide spaces for mnliies HB extending longitudinally of the kilnv at'the opposite sides of the portion of' the heating-up Zone adjacent the high'tem- The mulles I-IB may adidentical in construction and arrangement vwith the combustion chambersV employed in the construction shown in Figs. 1 to 7. The side walls of the kiln are advantageously inclined as indicated at B1o at the junction between the zones BB and CB to provide an easy path for products of combustion from the hot zone into the mul'les I-IB. Pipes T forming extensions of the muilies HB extend along the sides of the goods pathway through the linal portion of the heating-upzone. The ends of these pipes adjacent the ends of the kiln are connected -to headers T havin outlet aorts N connected to'an'exhaust fan M. AThe latter creates a positive dra-ft through the munies HB, and the pipeextensions of the latter, for drawing the products of combustion into the Amuiiles Vfrom the 'adjacent end of the hot Zone CB. y

The general mode of operation of apparatus shown in Figs. 8, 9 and 10 will be apparent without4 further description or illustration. In this apparatus, the goods -are in direct contact with the burning'gases in the high temperature lportion of the kiln. In consequence, theheat abstraction may be very rapid andthe length of this portion of the kiln correspondingly reduced. The provision of the inutiles HB in the heat-ingup zone into which the burning gases and products of combustionpass kprevents the marked and nundesirable differences in tem' perature between the top and bottom of the kilny chamber which would result if the pathV of travel of the products of combustion through the kiln chamber proper were prolonged to include the heating-up Zone of the kiln. Y

Those skilled in the art will understand that no matter how small the difference between the temperatures at the top and bottom of a kiln chamber at one point along its length may be, if the products of combustion or other hot gases are moved through the kiln chamber away from that point and are cooled in their travel there is a tendencyto concentrate a hotter portion-of the products or gases along the roof of the cooling chamber and to concentrate a cooler portion along'the bottom of the kiln chamber. This stratification which increases, other things being equal, with the distance traveled lengthwise of the kiln, produces a corresponding difference between the temperatures of thetop and bottom portions of the goods being heated. The muifles HB, with the open ended passages H in their walls set up convection currents of the kiln atmosphere in the portion of the kiln chamber in which the muflies are located which prevent marked differences between the temperatures at dierent levels in the kiln chamclaimed more specifically in my earlier application, Serial No. 300,443, led May 29, 1919.

While in accordance with the provisions of the statutes, I have illustrated and described the best form of my invention now known to me, it will be apparent to those skilled in the art that changes may be made in the forni of the apparatus disclosed without departing from the spirit of my invention as set forth in the appended claims and that certain features of my invention may-sometimes be used to advantage without a corresponding use of other features.

Having now described my invention, what I claim as new, and desire to secure by Letters Patent, is: l

l. The combination in a tunnel kiln having an Yelongated kiln chamber comprising two sections placed end to end,of a inutile extending longitudinally of the kiln and located in one of said sections and in communication with the other section at the junc- 4elongated kiln chamber comprising a laterally restricted portion and a laterally enlarged portion, of a muiile located in said laterally enlarged portion and open to the other kiln portion at its end adjacent the latter, means for supplying fuel and air for its combustion to the kiln and means for withdrawing products'of combustion coperating to cause the burning gases and products of combustion to follow a path of iiow extending longitudinally of the kiln chamber, and formed in part by the interior of the muflle and in part by the interior of the restricted kiln chamber portion.

3. 1n a combination open fired and Inutile heated tunnel kiln the combination with an elongated kiln chamber comprising two sections placed eiid to end, means for supplying fuel and air for its combustion to one of said sections, a muil'le located in the other section and extending longitudinally of the latter and open at its endV adjacent the :first mentioned section to the latter, and means for causing products of combustion to pass from the first mentioned section into said inutile. Y

1l. ln a combination open fire and mnflle heated tunnel kiln the combination with an elongated kiln chamber, of means-for supplying fuel and air for its combustion to the interior of one longitudinal section of the kiln` a mujlile located in and extending longitudinally of an adjacent section of the kiln and open to the lirst mentioned kiln section at its end adjacent the latter, and

means for withdrawing'picducts of combustion from the end of muiiie remote from the first mentioned kiln section.

5. The combination in a tunnel kiln having an elongated kiln chamber comprising two sections :placed end to end, of a inuiiie extending longitudinally of the kiln and located in one of said sections and in communication with the other section at the junction of the two sections.r air and'fuel supply means and means for withdrawing products of combustion coperating to cause the burning gases and products of combustion resulting from the combustion of said air and fuel to flow longitudinally of kiln along a path comprising the interiorof the inutile in the one kiln section and the interior of the other kiln section, said miiliie being formed with open ended passages in iis-1 its walls extending transversely of the length of kiln and providing paths Jfor convection currents of the kiln atmosphere upward past the niuilie through said passages and downward through a portion of the kiln chamber at the side of the mulie.

6. In a combination open fire and mule heated kiln, the combination with an elongated kiln chamber comprising two sections placed end to end, means for supplying fuel and air Jfor its combustion to one of said seotions, a Inutile located in the other section and extending longitudinally of the latter and open at its end adjacent the first mentioned section to the latter and means for 15 causing products of combustion to low from the first mentioned section into and through said Inutile, the latter being formed with open ended passages in its wall extending transversely to the length of the kiln and 20 forming paths for convection currents of the kiln atmosphere ilowing upward past the muflie and downward through the kiln chamber at the side of the muiie.

Signed at Pittsburgh in the county of 25 Allegheny and State of Pennsylvania this 23rd day of January A. D. 1920.

PHILIP DH. DRESSLER. 

